Arctic Armor 15' Round Above Ground Winter Cover - 4 ft Overlap is woven strong/long-lasting polyethylene tapes to produce a cover that will hold up to winters worst. We do not skimp on fabric! Arctic Armor above-ground cover use an extra foot of material—another reason why they are a great value! A 4-ft. overlap provides a better fit, esp. on pools with extra wide top-rails. This extra fabric also takes up some of the slack during windy weather, helping to prevent excessive wear and tear. Arctic Armor 12' Round Above Ground Winter Cover is constructed of an extremely tight weave fabric that does not allow light to pass through. Without sunlight, algae cannot grow! Our entry level cover has the strength and durability of cover costing twice as much. Rugged polyethylene scrim and coating means this cover can withstand winter’s worst. Arctic Armor covers are U.V. protected so they will last for years in direct sunlight. The cover’s black underside retards algae growth and heat sealed seams means a crystal clear pool next spring. Our gold grade cover is held secure by a heavy duty vinyl coated cable and tightener that is anchored to the cover by rip proof metal grommets. This rugged cover is built to last so it is back by a 15 year warranty.